The proposed project is a continuation of a project initiated in Finland in 1984 as a collaboration between the U.S. National Cancer Institute and the National Public Health Institute of Finland. The main activity been the Alpha-Tocopherol Beta-Carotene Lung Cancer Prevention Study (ATBC Study), a large randomized, double-blind, placebo-controlled, 2x2 factorial design, primary prevention trial testing the effects of alpha-tocopherol and beta- carotene supplements on lung cancer incidence and mortality. The primary objective of the present project is to follow all living participants in the ATBC Study (N=24,000) during the post-intervention period (1994-2000) to continue to monitor potential intervention effects on lung and other cancers and other morbidity and mortality endpoints. It is plausible that the effects of intervention with such agents will continue several years beyond the immediate period of administration of active agents. Monitoring cancer rates as well as morbidity and mortality from noncancer causes in the post-intervention period will allow us to determine if such effects exist and how long they last. Cancer incidence and all causes of mortality will be determined throughout the proposed 7-year period. Periodic contact with the study population is planned (years 2 and 5) which will permit collection of updated risk factor information including additional biologic specimens in some subjects. Another objective is to study the existing risk factor data and biologic samples for cancer control and causation hypotheses. These data provide an invaluable resource for the study of biochemical and molecular hypotheses. Such analyses will be more informative with the additional cases identified during the continued followup. In summary, the ATBC Study is the largest lung cancer chemoprevention trial ever conducted. Developed and implemented over the pst 10 years, it is an invaluable resource for cancer prevention research. Further follow-up of the 25,000 living participants from this intervention study is of undeniable importance in the field of cancer prevention.